1. Field of the Invention
The present invention relates generally to a wiper system for automotive vehicles. More specifically, the invention relates to an enclosed type of wiper system in which a wiper is received in a cavity defined by a windshield and an engine hood.
2. Description of the Background Art
In recent years, various types of wiper systems have been proposed. Some of wiper systems have a wiper receiving cavity between a windshield and an engine hood. Such a wiper system will be hereinafter referred to as an "enclosed type wiper system". Such wiper systems have been disclosed in Japanese patent First (unexamined) Publication (Tokkai Sho.) No. 59-53255 and Japanese Utility Model First (unexamined) Publication (Jikkai Sho.) No. 60-178263. In the disclosed wiper systems, the wiper receiving cavity has an opening through which the wiper goes in and out, and which is open and closed by means of a lid member. When a wiper switch is turned on in order to drive the wiper, the lid member is open by means of a lid driving means, and then, the wiper is drawn out of the wiper receiving cavity by means of a wiper driving means, to oscillate within a predetermined working-angle for sweeping raindrops off the windshield. On the other hand, when the wiper switch is turned off, the wiper is stopped within the wiper receiving cavity, and then the lid member is closed.
In the aforementioned wiper systems, the lid member of the wiper receiving cavity is respectively open and closed in response to turning ON and OFF of the wiper switch, and is usually closed while the wiper is not used. Therefore, when the vehicle is exposed in a very cold atmosphere, such as in winter, for a long time, it is possible that the peripheral edge of the lid member may become frozen to the opening edge of the wiper receiving cavity so that the lid member cannot open. When the wiper switch is turned on while the lid member is frozen, damage to, or failure of, the lid member opening and closing unit may occur.
In addition, in the aforementioned conventional enclosed type wiper systems, the working-angle of the wiper cannot be changed. Therefore, when it is or has been snowing, it is apprehended that the wiper causes snow on the windshield to be introduced into the wiper receiving cavity to become packed therein, since the lower angular position of the wiper is within the wiper receiving cavity.